Progress in integrating and optimizing production plans and schedules

Over the past twenty years two widely accepted approaches to integrated production planning and scheduling systems have emerged. The first approach was based on materials requirements planning (MRP). This approach emphasizes minimizing inventory while meeting order due dates. The second approach was heirarchical production planning (HPP). This approach emphasizes cost minimization and efficient utilization of capacity. This paper reviews the evolutionary development of each of these integrated systems and concludes by discussing the environment where each is best suited.     

Particle Size Effects on the Diffuse Reflectance of a Sucrose-Caramel Admixture

Decreasing the particle size of homogeneous colorant (caramel) from 68 to 28 microns increased lightness as predicted by the Kubelka-Munk theory. The presence of diluent (sucrose) reversed particle size effects, i.e., reduced caramel particle size decreased mixture lightness. Decreasing the particle size of the diluent, however, substantially increased the diffuse reflectance of the admixture, lowering its color intensity. The degree of color masking was determined mainly by the particle size of sucrose and to a much lesser extent by that of caramel. The dilution ratio and particle size of both colorant and diluent could be used to control the color of many food systems.     

Kinetics of Solids Leaching During Rehydration of Particulate Dry Vegetables

ABSTRACT: Air-dried and freeze-dried carrots were rehydrated in a computerized mixing system, and the medium was analyzed for sugar content with high-performance liquid chromatography (HPLC) and for total organic carbon (TOC). Leaching of solids was significant at very short rehydration time. Understanding the mechanism of the leaching process could provide information required for simulation. TOC values were significantly higher than those derived by HPLC, indicating that other organic components were extracted. The difference between TOC and HPLC values varied with time, indicating the existence of a different mass transfer rate. Sugars and TOC values followed an exponential behavior. Quantifying solids leaching is important for modeling and simulation of the rehydration process and for product optimization.     

Oil Uptake in Deep Fat Frying as Affected by Porosity

The porosity of a restructured potato product ranged from 0.089 to 0.168 after fluctuating subfreezing storage temperatures. A linear relation was found between oil uptake during frying and porosity prior to frying. Bulk and particle density, and porosity were monitored for up to 5 min during deep-fat frying. Particle density increased gradually, bulk density decreased and porosity increased noticeably. After an initial short period, oil uptake correlated linearly with porosity of the fried product. A new term, “net porosity” which excluded the void volume occupied by oil was developed for describing the oil uptake mechanism.     

犊牛的管理

针对国内牛场管理方面专门论述较少,从犊牛管理实践出发,简要介绍了犊牛识别系统、犊牛的去角、犊牛垫料的选择与管理、犊牛奶桶的正确洗涤方法、犊牛饲料的存放以及劳动力的管理等内容,对管理内容进行了界定和阐述。     

UPGRADING SPENT LAYER MEAT BY MECHANICAL DEBONING AND FURTHER PROCESSING

Spent layer chickens, an underutilized, inexpensive source of animal protein in the United States, were used to produce an acceptable all chicken frank following mechanical deboning of the chicken parts without pregrinding. The franks were subjected to shear tests and compared to two well-known commercial brands of chicken franks for overall acceptability by an untrained 59 member panel. The franks produced from mechanically deboned spent layer chickens (Lab franks) had greater resistance to shear than the two commercial brands and the panelists showed significantly greater preference for one of the commercial brands. Comments of the panelists indicated the texture of the lab-prepared franks was tougher than the two commercial brands. However, 12 members of the panel stated the lab-frank texture was tender. Collagen content of the spent layer franks was no higher than for the commercial brands. It is therefore concluded that the toughness could have been due to the nature of the myofibrillar proteins. Such toughness could be modified by tenderizing enzyme treatment of the raw material to produce varying degrees of frank softness or firmness depending on consumer preference.     

Elastic Moduli of Glasses by a Dynamic Method

The elastic moduli and speed of sound of twenty-three optical glasses, a series of Na₂O₃, CaO₃, SiO₃, and B₂O₃ glasses, and some specimens of fused silica were measured by a dynamic method. Each specimen, in the shape of a prismatic bar, was vibrated in four different ways: longitudinally, flexurally on the wide side, flexurally on the thin side, and torsionally. Good agreement was found on Young's modulus as determined by the first three methods. The torsional mode was used to obtain the shear modulus. Statically and dynamically determined values of Young's modulus for six sample glasses also showed good agreement.